


The Sea of Clouds Under the Moonlight

by jay792



Category: Hunter X Hunter
Genre: Aged up characters, Gen, M/M, Nanika is living in a crystal in this one, and an eventual motorcycle, basically Castle in the Sky, cameo appearances from other characters too, lots of blimps
Language: English
Status: In-Progress
Published: 2021-01-27
Updated: 2021-01-31
Packaged: 2021-03-12 14:26:51
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 10,152
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29012001
Author URL: https://archiveofourown.org/users/jay792/pseuds/jay792
Summary: Long ago, the Zoldyck family used to rule over Laputa, the floating city, but that legacy has all but faded from memory. Now, centuries later, Alluka Zoldyck awakens to a power held long ago by her forefathers, but not every party is happy with this development. Can Killua keep his sister safe? With the help of one Gon Freecss, son of famed archaeologist Ging Freecss, the three may be able to uncover the dormant secrets of the ancient city before it is too late for them.A Castle in the Sky AU
Relationships: Alluka Zoldyck & Killua Zoldyck, Gon Freecs & Alluka Zoldyck, Gon Freecs & Alluka Zoldyck & Killua Zoldyck, Gon Freecs/Killua Zoldyck
Comments: 3
Kudos: 13





	1. Prologue - A Starry, Moonless Night

PROLOGUE - A Starry, Moonless Night

* * *

“On a dark, clear night, such as this one, when the stars are at their brightest, you can catch a glimpse of the floating city as it soars by, high up in the clouds.”

Ging angles his son’s head up so he looks at the blanket of stars, but he’s certain the baby is more interested in sucking on his tiny fist than he is in the story. Undaunted, he presses on, needing no audience for this. “That’s what the stories say, anyway, but there’s no one alive today who’s actually set foot up there. Your old man’s going to be the first in many, many centuries. Mind you, I’m not doing it for the money, though there’s bound to be plenty of treasure gathering dust.” Ging shifts the child to rest on his hip, his weight nearly forgotten as he looks up, straining his eyes for a glimpse of that shining beacon passing overhead. So far, no luck, but Ging is patient, at least in this regard.

“No, there is something far more valuable up there. Knowledge. So much knowledge, kid, things we’ve since forgotten as a species. Things we’ve never known about before, even. I’m going to be the one to bring it all down here, and we’re going to _leap_ forward. You’ll see.”

“Didn’t Prometheus try to do the same thing?” a voice calls out from the darkness. “Look how _he_ ended up.”

Ging turns around to find his cousin watching them from the road, hands on her hips and a small scowl on her face. He offers her a smirk in return before turning his gaze back to the heavens, which only makes her roll her eyes and begrudgingly approach them until she’s standing beside the pair.

“Who cares about what happened to Prometheus? He offered humankind the gift of Fire. His legacy amounts to so much more than just his life. Besides, Mito, I’m not trying to steal fire from the gods. The civilization that lived up there were very much human. Royal scum, probably, but still human in the end.”

Mito sighs and gently pries the baby from Ging’s arms. He coos softly in protest but is soon cuddled up against her shoulder with a placid smile. She holds him protectively, even angling him away from Ging as she rebukes him. “ _Please_ tell me you did not take little Gon out of his crib and carry him all the way out here just so you could ease your conscience before you leave. Again.”

Now that he doesn’t have Gon in his arms, Ging seems to be at a loss what to do with his arms, and he ends up crossing them tight across his chest, trying to shield himself from the sudden bracing cold. “I don’t need to justify myself to anyone,” he says through gritted teeth. “But Gon is my son, and he should know about this.”

“He’s not even two years old yet, Ging. I don’t think he would understand anything about old floating castles if the whole damn thing came crashing down on us right here, right now.” Mito looks up at the sky with suspicion, as if saying this is enough to will the event into actually happening. The sky, however, remains unchanged, and all she can hear are the crickets and the wind blowing through the trees. “At least you have enough sense to leave him here instead of taking him out there with you, but by god, if he doesn’t turn out like you, I’ll count myself lucky.”

Ging huffs, but he has the sense not to try and defend himself against the accusation. Because ultimately, Mito is probably right - not that he’d ever admit it. Gon was… certainly not planned, and having a kid around is more of a hinderance than anything else to an archaeologist. Still, Ging comforts himself with the fact that what he is doing is leaving a legacy for his son, that he isn’t giving the proverbial gift of Fire to a nebulous ‘Humanity’, but instead to a very tangible form that somehow, miraculously, came from him. So it does somewhat ease his mind to know he can just go off exploring and Gon will be taken care of.

“I’ll be back before he learns to walk,” he says after a moment’s pause. Mito feels that her cousin might only be trying to fill in the silence, but Ging is serious about this. She holds Gon closer to herself, gently rocking the boy to sleep.

“When you get back here, he’ll probably be able to read and write already,” she shoots back, keeping her eyes trained on the sleeping figure in her arms. She can feel her eyes prickling as warm tears well up in them, but she refuses to cry, so she keeps her head down and her brows furrowed almost stubbornly.

Ging offers a non-committal grunt as he bends down and shoulders a large bag. “Wouldn’t _that_ be convenient…” he mumbles as he stands again, already turning towards the horizon, where a ship is approaching the harbor.

“So that’s it then?” Mito asks quietly. “You’re off?”

Ging nods, barely pausing before he takes the first step down the hill. “No time like the present.”

“Aren’t you even going to say goodbye to him?”

There is a pause before Ging turns to face his cousin, a skeptical look on his face. “You said it yourself. He probably doesn’t even understand what I’m saying, right? So what’s the point?”

Mito opens and closes her mouth a couple of times as she tries to find the right words, but in the end, all she does is grumble and stomp her feet. “You can be _infuriating_ sometimes, Ging Freecss.”

Ging grins and just turns around again, focusing on putting one foot in front of the other. However, his cadence is broken once again, this time by a startled little gasp from Gon, who’s suddenly wide awake with his hand outstretched, as if reaching for the sky. High up there, something is shimmering, like a jewel soaring through the ocean of clouds. It is there for a heartbeat and gone the next. Ging looks awestruck, but he recovers quickly and simply lets out a hearty, triumphant laugh before waving goodbye and finally making his way down the hill.

Mito stays up there, staring skyward, until the ship leaves the harbor, holding onto Gon as if he could run through her fingers at any moment and be blown away by the wind.

**Notes for the Chapter:**

> Contrary to what you might think after reading this prologue, the story is actually centered mostly on Killua and Alluka, but they won't actually make an appearance until the next chapter. Gon will come back, obviously, filling in the role of Pazu, but for now, have him as a tiny baby stargazing.
> 
> This was a fun chapter to write! Hope you all stick with me as we go on an adventure with blimps, pirates, and magic crystals. Updates will come as I am able to keep on writing, given that work takes up most of my day, but I'll do my best to actually get stuff done at regular intervals. I have several chapters outlined for now, at least.
> 
> Find me on Twitter @jay792


	2. Chapter 1 - In Search of Repose from my Heart-rending Woes

**Summary for the Chapter:**

> Alluka and Killua are living in a secluded valley in the mountains. On the eve of an anniversary, Killua reminisces about the circumstances that brought them out there in the first place.

**Notes for the Chapter:**

> The chapter title is a line from the poem “The Fugitive” by Friedrich Schiller, which I feel encompasses the general mood of the scene.
> 
> Some mild content warning for this chapter: Hisoka makes a few transphobic remarks as he does not respect Alluka's pronouns, but at least for this story, I've decided that the Zoldyck family DO all refer to Alluka using she/her. There are mentions of someone being locked up for a long time, and there is some violence around the end of the chapter. If any of this isn't your jam, you've been warned.

CHAPTER 1 – In Search of Repose from My Heart-rending Woes

* * *

Alluka takes a deep breath, almost as if steeling herself, before taking a bold step off the verandah and down onto the dew-covered grass, shivering pleasantly at the cool feeling beneath her bare feet. She then giggles and takes off at a run, arms outstretched, wandering towards the goats that Killua let out a little before sunrise, wishing to greet each one by name. She does this every morning, and the sight of it never fails to warm his heart. Killua watches her from the verandah, hands busy repairing a basket, and he can’t help but smile.

Unbeknownst to his sister, today is a special day, an anniversary of sorts, as five years ago, to the day, Killua walked out of the Zoldyck family manor, vowing never to return, though he’s never actually discussed the particulars with Alluka as to why he came to that decision in the first place. Every time she’s brought it up, Killua has grown quiet and withdrawn, so Alluka’s done her best to steer clear of the subject for her brother’s sake. It wasn’t as if she remembered much of it anyway, even if she had already been 11 at the time. Patches of her past were just… hazy at times.

As the first rays of sunlight pierce through the dawn’s gloom, Alluka starts to sing, a simple melody which makes the goats regard her with curiosity. She grabs the hem of her skirt and starts swaying in time to the rhythm, bowing to the animals as they bleat in response. One of them, a kit named Charcoal, runs up to her and nuzzles her rather forcefully until they both topple over. Alluka laughs, overjoyed, wrapping her arms around the goat’s neck and bracing herself against it as she sits back up. She finally seems to spot Killua, who’s put the basket down in favor of resting against the wooden railing, chin on his hand, to get a better look at the scene, and she grins and waves at her brother, who, delighted, laughs and waves back at her with just as much enthusiasm. As she lets go of the goat, it immediately reaches for a necklace hanging from Alluka’s neck and begins munching on the rope. The girl gasps and scrambles to wrestle it back from its mouth.

“Bad girl, no!” she chides the animal, though even from where he’s standing, Killua can already hear her giggling.

The necklace might not look like much; it is a simple black string wrapped around a tear-shaped blue crystal that’s roughly the size of a river rock. One might even dismiss it as a trinket, something a child might find during a short hike. And yet, it is this very crystal that made Killua leave everything behind, five years ago.

Five years, and Killua still feels like he can’t let his guard down. Just because his family hasn’t found them _yet_ doesn’t mean they won’t come eventually, even to such a secluded place as this valley where they’ve found sanctuary and made a home for themselves. How much longer can they keep this up? The question sits heavy in Killua’s mind, but at least he can allow himself to celebrate this small victory. They’ve been able to mostly disappear from the world for this long, and that is more than Killua ever expected to achieve.

As Alluka begins to sing again, Killua is suddenly reminded of another time, another place, far from this meadow. He had been ten then, Alluka nine. Even back then, his sister had always loved to sing - to him, to any animal she might find, even to herself, and Killua would just sit back and watch over her. Alluka liked to wander the woods of the family estate, and she was known to get lost if she wasn’t paying attention to her surroundings (which was often the case). Killua had tasked himself with making sure she always found her way back safely, no matter where she ended up.

[*] [*] [*]

One day, Killua had gotten careless. They’d been out exploring the woods far from the house, and he’d lost sight of his sister for what had only felt like a moment, but when he had finally caught up to her, hours had passed, and night had fallen over the estate. If she had not been singing, perhaps he might have missed her entirely, as she was in a part of the woods neither of them was familiar with yet. His search had led him to a small clearing. Alluka had been sitting at the edge of a pond, cradling something shiny in her hands. The melody she was singing was new to Killua, but the tune had somehow felt familiar, stirring something deep within him. It had felt like a sacrilege to interrupt her, so he’d waited until she was done and the light was fading in her hands.

As silence settled back in the forest, he’d finally braved to ask, “Hey, sis, what’s that you got there?”

Alluka had turned to look at him, a proud smile on her face, and she’d opened her hands to show him a crystal, tear-shaped and the size of a pond stone, shining with a soft, pulsing blue light that somehow felt organic, and she’d simply said, “I made a new friend!”

Back then, Killua had been too young to understand the implications of this event, and he’d simply walked up to Alluka to take her hand and carefully backtracked his way to the house. However, as soon as news of the appearance of Alluka’s crystal traveled the house, a change had occurred within the family. Not even a week later, he’d suddenly been forbidden from playing with Alluka anymore, and his sister had been confined to her room until further notice. No amount of protesting, arguing, pleading, or rebelling from Killua’s part had made his parents change their mind, and in the end, Killua knew he had no choice but to comply. This was the way things were now, and he was powerless to stop it.

He soon started listening in on the adults whenever he found them talking in urgent whispers, and he slowly began to understand something. The crystal Alluka possessed was a rare item that hadn’t been seen in the world in many a year, longer even than their grandfather had been alive. The reappearance of the crystal forbode _something,_ but no family member could agree on what that might be. All they told Killua was that it was dangerous, and that Alluka was being kept locked away for her own safety.

When Killua had gotten tired of getting the same vague answer over and over, he’d decided to take matters into his own hands and investigate on his own. His family had tried to keep him busy with other tasks, but somehow, he always found the time to get back to this, determined not to give up on Alluka. Going back to the pond in the forest had yielded no results, as it really did seem to be nothing more than a stinky old pond. Poking around in the family library was too daunting a task for him, with so many books and no clear place to start. And after that, he’d been at a loss as to what to do. As the weeks had turned to months, Killua had come to a very simple conclusion. This wasn’t something he was going to discover on his own, and since no one in the house was going to give him a straight answer, he would have to go to the source and get those answers himself.

Killua had often seen his father and oldest brother conferring in the library, poring over thick, dusty tomes, and looking at maps. Sometimes, strange people would come into the house to join them in their meetings, and Killua was warned to stay away when that happened. Which was why, of course, the next time one of these men came to the house, Killua snuck into the library beforehand to listen in, desperate to get any kind of information.

It was early morning, and Killua had already been waiting in a cramped space behind two bookcases for over an hour. He had been thinking about at least stretching his legs before he couldn’t feel them anymore, but then he’d heard voices approaching the library, and he’d been left with no choice but to stay put.

His father’s voice travelled all the way down the hallway even before the doors opened. Silva seemed to be in the middle of a discussion already, “…No, the texts say that hellfire rained down from the sky, obliterating the city and everyone in it. The translation might even be inaccurate and be referring to a _nation_ instead of just a city.”

“And you’re certain this was the work of the crystal how?” Illumi, his voice as deadpan as ever. Killua had trouble picking up exactly what his brother was saying, but he didn’t dare move. His father may be stern, but Illumi was downright terrifying when he wanted to be, and Killua didn’t even want to imagine what would happen if they found him in here.

“The journal,” Silva said simply, and all parties seemed to accept that as an answer. “If the bearer had enough power to raze an entire city to the ground on a _whim,_ why are we even opening it up for discussion? That crystal should be destroyed before someone comes for it and uses it against us.”

A third voice joined in then, one Killua wasn’t familiar with. They sounded almost amused by Silva’s viewpoint. “That’s assuming you haven’t learned how to use it yourself before that happens. The Zoldycks of old had an entire fortified city at their disposal, a kingdom. They were nigh untouchable. If that power has been made available to you again, I don’t understand why you’re still hesitant to make use of it.”

“Hisoka’s right.” Illumi again, and Killua could hear papers being moved around as the men sat down at a table in the middle of the room. “The Zoldyck name used to be revered back then. Their might made other kingdoms quake in their boots and fully submit to us. What our family is today is a mere shadow of what it once was. We should be _ashamed_ of ourselves for thinking we’re anything but parasites living off the remnants of that power. Father, think of what we could achieve with it if we learned how to use it once more. What it could do for our House. And what are we doing instead? We’re wasting an opportunity, perhaps the only one we’ll ever have, by letting an 11-year-old _brat_ safekeep it.”

“Who’s to say he’s the only one who can use it, anyway?” That had to be the newcomer, Hisoka. Killua wanted to stand up and shout that Alluka was a _girl,_ damn it, but perhaps now wasn’t the time to be defending his sister’s honor, even when he knew no other family member would stand up for her in this regard. “Take it away from him and keep the stone for yourselves. This argument is moot until you actually have access to that power, anyway. For now, it’s just rotting away in that room as we speak.”

Illumi hummed in agreement. “The journal didn’t specify anything about a single user restriction, so it _should_ work. However, Alluka won’t let us anywhere near it. You’ve seen what she can do with it already…”

“Nasty business,” Hisoka agreed, though his tone of voice actually suggested he had enjoyed whatever Illumi was referring to.

“No.” Silva’s voice was as hard as stone, and just as unyielding. “Illumi, you are not touching that stone. _As long as I am head of this family, no one is using that power.”_

A long, tense period of silence followed, and Killua imagined the three men must be sizing one another up. It was almost tempting to sneak a peek, if only to see what the stranger looked like. Killua was even starting to lean to the side when a book slammed shut all of a sudden, cutting the silence short, and Killua jolted in place, heart beating a mile a minute.

“Fine. I have to respect your decision, as head of the family. However, father, you said it yourself. No one should be using that power, and that includes Alluka. We cannot allow her to keep developing her powers. If she forges a stronger link with the crystal, it really might be too late for everyone, yourself included.”

Silva grumbled at that, and after a moment, he sighed heavily and conceded. “At least we all agree on that. Alluka needs to be dealt with. If she’s already been using its power the way she has, then she’s probably too far gone already.”

“I’ve seen her in her room, talking to herself. She must be weak-willed if the crystal is corrupting her spirit already. Such a shame, but the Zoldyck crystal really shouldn’t be used by someone so young in the first place. The fact that she found it must have been nothing but a fluke. I’ve always said they’re all too young to be left wandering around like that. Children should be kept in a tight leash until they’re old enough to know better.” Illumi started pacing the room as he spoke, though Killua could barely hear his soft footfall, partly because his brother’s words had shaken him to the core. He was visibly shivering, thinking about the implications of what ‘deal with Alluka’ might mean for his sister, but he couldn’t move, couldn’t think. Not yet.

Illumi continued, unaware of the effect his words were having. “Me, on the other hand… Father, you know I can keep it safe. Only until we decide what to do with it, of course. Trying to destroy it willy-nilly would be a bad idea, would it not?”

“Oh? Do you think it might explode?” Hisoka hummed, sounding more interested in this by the minute.

Silva’s voice followed, probably trying to keep Illumi from taking control of the situation any further. “It’s definitely a possibility, but I don’t want to have to find out.” A loud noise followed, which led Killua to believe that Silva had just slammed his hands on the table. “I hate to admit it, but you’re right. And leaving it in Alluka’s care is just inviting another disaster into our hands... Fine. Do it.”

“You heard him, Hisoka. The faster we do this, the better it’ll be for the whole family.”

Hisoka laughed, and Killua felt his skin crawl at how _delighted_ he sounded about the prospect. “Oh yes, I won’t dally. Your little problem should be _dealt with_ before the week is out. Now, if you don’t mind… I have things to prepare if I’m to keep that promise.”

“Right.” Illumi stopped just a few feet away from Killua’s hiding place, and Killua willed his hands to stop shaking. No one should be able to see him here. He was fine. He was fine. He couldn’t let himself be discovered because oh god, _what if they dealt with him too?_ What would become of Alluka then? After a moment, however, his brother finally turned back around and started walking the other way. Killua allowed himself to breathe out again. “Oh, and Hisoka? Try not to make such a mess this time.”

“Mm, you’re no _fun_ , Illumi.” Hisoka clapped his hands together and stood up, dragging the chair he’d been sitting on. Judging by his footsteps, he was heading for the door. “I’ll take my leave, then.”

Silva grunted, apparently the only form of acknowledgement he was willing to give the man. “We should leave too. My father should have some useful information regarding the crystal. Illumi… if you’re really planning on safekeeping it, you better come prepared.”

Illumi sighed, and Killua could hear him gathering up everything they’d set on the table. “You raised me, father. You should know I _always_ come prepared.”

The door to the library closed behind them, and their voices slowly faded away, leaving the room seemingly empty but for Killua. A stuffy, oppressive silence soon settled in the locked room as the minutes went by, but Killua hadn’t dared move for another hour. He was trying not to hyperventilate as he processed this information. Alluka. They were going to kill Alluka if he didn’t do something to stop it. But what could he do? Whoever this Hisoka character was, he’d sounded confident enough that he’d be done with this within the week. Killua couldn’t even find the strength to stand up right now, much less to stand up against these men who would harm his sister for the sake of ‘protecting the family’. As far as he knew, they craved whatever mystical power that crystal offered, and more than anything else, they wished to control that power. But what could Killua do, especially when all of this was so over his head?

The answer came to him then, plain and simple. _Run._ He could not fight against his circumstances, but he could do what he’d always done before: lead Alluka to safety.

By the time Killua had finally left his hiding spot, his legs felt leaden, and every step was absolute agony, but he knew he had to keep moving before he lost his resolve. As he walked down the hallway to his room, he felt as if he were being watched, but Killua knew this was just him being paranoid. No one had seen him, and no one would know what he was planning now. He himself wasn’t sure what that plan was yet, so for now, he’d be taking it one step at a time. First, pack a bag, then get Alluka, and after that… get the hell out of here. The rest would have to come organically.

The first step had been easy enough. Killua had managed to find a bag that could fit his more comfortable, durable clothes, various toiletries, and some food he had managed to sneak out of the kitchen. It didn’t even weigh that much, and he had a feeling it would be important to travel light.

The next steps proved to be a little harder. Ever since Alluka had been confined to her room, a guard was kept posted at her door at all times. Over the years, Killua had tried many times to approach the door, pleading with whoever was guarding it at the time to let him in. The answer was always ‘No,’ and he didn’t expect this time to be any different. Which is why he didn’t try going through the door at all.

While there weren’t any large windows in Alluka’s room, there was a ventilation shaft leading toward it, and Killua supposed no one had thought his sister would try to hoist herself up into the dusty, cramped duct. Killua himself barely fit in, and he had to be glad that he had thought to leave his bag behind before squeezing in. Otherwise he’d be stuck by now. It had taken longer to find his way through the maze of ducts than he would ever have expected, but eventually, he’d heard singing and had once again followed his sister’s voice until he found her.

Alluka had been sitting on a plush carpet, humming to herself as she combed her hair. Once this task was done, she had gingerly set the brush down on her lap and looked at herself in the mirror. “I think that should do it, Nanika,” she declared proudly, and although Killua heard no response, Alluka giggled and nodded.

He took this moment’s pause to call for Alluka from the grate on the ceiling. “Alluka… Alluka, up here,” he hissed.

Alluka stiffened for a moment, narrowing her eyes as she looked around the room. It seemed to take her a moment to place the voice, but as soon as she recognized it as her brother’s, she gasped and sat up straighter, frantically searching for him. “Killua?!”

Killua felt a sudden knot in his throat, and he had to swallow thickly to keep himself from crying. “Yeah, it’s me,” he said softly. “Up here. I’m… I’m coming down, ok? Stand back.”

Alluka finally seemed to locate the grate, and she definitely seemed to be noticing it for the first time, judging by her expression. She nodded mutely and placed a cushion underneath it before stepping back, cradling her brush to her chest as she looked up expectantly.

Killua had to tinker with the grate for a moment before he finally managed to pry it open, and then he had to wiggle around rather uncomfortably in order to actually fit through it, but after a few awkward minutes, he was landing on the cushion with a soft thud. After his journey through the guts of the house, he was now a dusty, disheveled mess, but Alluka didn’t seem to care at all. Before Killua could so much as dust himself off, his sister was already running up to him and hugging him tight enough to squeeze all the air out of him.

“I knew you hadn’t given up on me,” she whispered against his shoulder, burying herself deep against his shirt. “They told me you didn’t wanna play with me anymore, but I knew they were wrong.”

Killua took a shuddering breath as he held her in his arms. “Of course I didn’t. I would never give up on you, Alluka. I’m sorry I wasn’t able to come sooner, but I’m here now. Your big bro’s here and he’s not going anywhere ever again, ok?”

“’kay,” Alluka echoed, and Killua knew his sister was probably doing her best not to cry right now, same as him. So Killua forced himself to put on a happy face before he leaned back and looked into Alluka’s face, offering her what he hoped was a reassuring smile. To his relief, Alluka smiled back, even as she sniffled. Now he had to convince her to come with him, preferably without worrying her too much. Killua cleared his throat.

“Say, Alluka… are you happy here?”

Alluka seemed to consider this for a moment before hesitantly shaking her head. “I miss the forest. And I miss you, most of all. We get bored in here.”

 _We?_ Killua didn’t know what Alluka meant by that, but now wasn’t really the time to ask. “Would you like to be able to hang out with me again, all the time?”

This time, Alluka didn’t even need to think about it. She nodded eagerly, reaching for Killua’s hand and holding it tight, as if he would suddenly disappear if she wasn’t touching him.

“Then we need to go, okay? Just the two of us. It’ll be like… an adventure. We can go see a lot of other woods and sing to a lot of animals and… and have fun together.”

Alluka clung to his every word, eyes open wide. “What about the house?”

Killua shook his head. “We’ll find our own house. And you’ll be able to come and go as you please. No more staying in your room all the time.”

Alluka turned to face the mirror again, and she stared at it for a long moment without saying anything. It took Killua a moment to realize that Alluka was wearing the crystal she had found a few years back, and that it was now hanging from a piece of black rope she seemed to have fashioned herself. That, and that the crystal was now glowing faintly, its color somehow muted. He was so transfixed by this, that it took him a moment to realize Alluka was calling him.

“H-huh?”

“I said, ‘Okay.’ Let’s do it, just us.”

Killua breathed out a sigh of relief and nodded. “C’mon, then. Let’s pack you a bag so we can go before anyone sees us.” He gently pulled Alluka to her feet, and she quickly got to work, packing only a few items of clothing, her hairbrush, a notebook, and a small dolphin plush toy that Killua didn’t have the heart to tell Alluka to leave behind. It felt like a lot, but at the same time, it was so little.

“Is that everything? I don’t know if we’ll be able to come back for the rest…” he told her as he looked around the room, trying not to think too hard about the fact that Alluka had been kept locked away in here for almost three years now.

“Mhm, this is everything I really like, anyway.” Alluka looked up at the ceiling, and Killua followed her gaze. From this side, the grate had been nearly invisible, painted over with a childish drawing of a smiling sun. Now, with the grate hanging open, the entrance almost seemed to be shining, with the cartoonish sunbeams illuminating the exit. “Are we going that way?”

Killua nodded, but then he realized something with mounting dread. He hadn’t brought any rope with him, and there didn’t seem to be anything tall enough to get either of them back up there, even if Alluka stood on Killua’s shoulders. He was trying to come up with a solution, thinking about piling up all the furniture and maybe throwing his sister up in the air to at least let _her_ leave this room, when Alluka tapped him on the shoulder. Killua suddenly realized his shoes weren’t touching the ground anymore. In fact, he was now floating halfway up the room, and the realization was so jarring, he started flailing around until he did a backflip in the air and gasped. Alluka giggled softly beside him, and Killua didn’t know whether or not to start panicking when he noticed that she was floating as well.

“It’s okay,” she told him, reaching for his hand again. Killua held onto it, feeling more grounded (though certainly not literally) just by performing such a simple, yet familiar, gesture. “I just realized we had no way of getting up there, so I asked for some help.”

Killua nodded dumbly, letting Alluka hoist him up back towards the grate. He grabbed onto the edge and scrambled inside, making sure he was facing the right way before giving Alluka some room. She made it look so much easier, gracefully pulling herself in and settling inside the duct with her bag pressed tight against herself. Killua carefully closed the grate again, trying to leave it exactly as he had found it, and then he craned his neck to look back at his sister.

“Stay close, okay? I don’t want you to get lost in here.”

“’kay,” she whispered. “I’ll keep quiet too. I don’t wanna get you in trouble.”

Killua smiled softly. “Trust me, Alluka, you just saved us a lot of trouble by doing that back there. That was awesome, thank you.”

Alluka paused for a moment, looking rather shocked at the sudden praise, but then she beamed at her brother and nodded. Killua started moving then, doing his best to backtrack to the place where he’d come in first, and any further conversation had had to wait until they could safely talk again.

By the time they’d emerged outside the house, the sky was already tinged a lilac hue, the shade of a fresh bruise, and the temperature was dropping quickly. Killua helped Alluka step outside, and as he patted himself clean, Alluka took a deep breath of fresh air and started walking around in a small circle, taking in the sights and smells that were so familiar to them both. Killua let her stretch her legs out for a moment, knowing what this would mean to her, but eventually, he had to walk up to her and gently nudge her.

“We have to move on now,” he reminded her as he reached for the backpack he’d hidden in the bushes. “We’ll have to be very careful. We don’t want someone to see us, or we won’t get very far.”

Alluka nodded, quickly holding onto Killua’s hand to let him lead the way, as he’d always done for her. Killua had been extra careful as he walked into the forest, moving through the trees like a shadow. He didn’t know how long it would take them to notice Alluka’s absence, but it couldn’t be more than a few hours. He would have to be quick but cautious. The next step would be to leave the property, and after that… after that, he still had no idea what they would do. It wasn’t like he had any friends or family who could give them shelter, but at least, he told himself, they’d be out of reach, if only for a moment.

Killua was fairly certain he remembered the paths each guard usually patrolled during the evening, and he tried to skirt past these areas. Thankfully, after years of wandering the woods with Alluka, he was fairly certain he knew them better than any one person working for the family ever would. Every step they took led them further away from the house, from the family that would see their child die if it meant restoring some dumb legacy, and as they put more and more distance between them, Killua felt lighter, surer of himself. If this was all he could do for Alluka, then that was what he would do. So far, everything was going according to plan, if this could even be called a plan at all. With any luck, they would be able to sneak out unnoticed and put some distance between themselves and the grounds before…

“Rather late for an evening stroll, isn’t it, young masters?”

Killua froze in his tracks, and he immediately moved to guard Alluka, placing himself in front of her. However, the person stepped out of the shadows in a completely different direction than what he’d anticipated, which made him falter. The looming figure standing before them was Tsubone, one of Silva’s head guards. Which basically meant they were done for. Tsubone wouldn’t let them slip away unnoticed. She’d report them to their father, and they’d be taken away. Killua knew his chances of escape had been slim to begin with, but to think that they’d been caught even before they left the Zoldyck estate was just… crushing. What he had not been expecting was for Tsubone to kneel down before them, regarding Alluka’s crystal with awe.

“So it’s true,” she breathed out. “The Zoldyck crystal really has reappeared. To think that it would have chosen _you_ , child…”

Killua decided to try his luck. Any chance he could get to have Alluka leave this place, he would take. He defiantly stepped between them, shielding Alluka from Tsubone with as much determination as he could muster. He looked into her eyes as he softly pleaded his case. “She was being kept locked away because of it. Please, Tsubone, something terrible is about to happen if we don’t…” Killua trailed off. He couldn’t explicitly say it, but he had a feeling Tsubone understood that they meant to harm Alluka in some way. She regarded both children for a moment before looking around, as if making sure they weren’t being watched.

“Follow me, young masters,” she said softly, resting a hand on each of their backs and leading them down the same road they were on. After some time, Tsubone veered right, away from the path, and paused at a seemingly random spot, where she parted some bushes and pulled on something heavy. As it turned out, she was opening a cellar door that had been carefully concealed among the greenery. Tsubone bowed and pointed to an old stone stairwell that led deep underground. “If you follow that path, it will lead you to an exit down by the river, about five miles south. Your family doesn’t know about this exit any longer, as it hasn’t been used since your great-grandfather’s time. My family has been serving the Zoldycks since they were still the just rulers of a kingdom, young master, and we have always prided ourselves in that job. If the crystal has manifested again, that means a great change is upon us. Go, both of you, with my blessing. My duty is to you as much as it is to master Silva, after all.” She took a deep breath and bowed low. “Once you find your way out of the tunnel, head west and look for a cabin by the riverbend. Look for a girl named Amane; she can help you. Now hurry, before they catch us here.”

Killua was stunned into silence. Could he really trust Tsubone, a woman who was known to be entirely loyal to his father only? However, there had been… something different about her ever since she spotted the crystal, and Killua thought he could recognize it as reverence. To follow her instructions would be to take a step into the unknown, but hadn’t he decided to let the plan develop organically? Somehow, this felt like they were heading in the right direction. He finally nodded and took a step inside the cellar, making sure the path was safe for Alluka. He turned to look at his sister to get her to join him, but Tsubone held up her hand, asking him to wait.

“I would ask for a moment with young master Alluka first, if that is alright. Don’t worry, young master Killua, I won’t keep you long, but this is important.”

Killua didn’t particularly want to agree to this. What if it was a trap? What if the moment Alluka was far away enough, Tsubone closed the cellar door and left him trapped in here alone? He was about to protest, but Alluka herself shook her head to stop him. Deflated, Killua sighed and waved his hand to urge them to hurry it up. “Fine. If Alluka says it’s okay, then do it. But don’t waste our time, old lady. We really have to go.”

Tsubone huffed, mumbling something about a lack of manners in kids these days, but Killua didn’t particularly seem to care. He stared at Tsubone as she led Alluka away, to the side of the road, far enough that he couldn’t listen in on their conversation. Tsubone crouched beside her and asked her something. Alluka nodded and showed her the crystal without letting Tsubone touch it, and Tsubone nodded and leaned in close to whisper something in Alluka’s ear. Alluka’s expression suddenly darkened, and she seemed to somehow look more resolved. She turned to look at Tsubone and nodded firmly, repeating whatever it was Tsubone had told her. The old woman offered Alluka an encouraging smile, and Alluka surprised Killua and Tsubone both by suddenly hugging her. Tsubone stiffened for a moment before hugging Alluka back, even rubbing her back for a moment before stepping away. She then urged the girl to follow Killua inside, and Alluka nodded and ran after her brother.

“What was all that about?” Killua couldn’t help but ask, trying to peer back at Tsubone to see if she was still there, watching them. Alluka, however, did not seem willing to respond to that, and she had just pulled on Killua’s arm to get him to start walking.

“Come on, Killua! We need to get moving, right? So let’s go, let’s go!”

It was hard to argue with that, so Killua nodded and once again held onto Alluka’s hand, leading her into the dark, holding a lantern to light their way. The cellar door closed with a resounding thud behind them, and the sound echoed down the tunnel for a long, long time.

At some point, Killua and Alluka had crossed past the boundaries of the Zoldyck estate as they made their way through the dark tunnel, and by the time they emerged out the other end, with the early morning already upon them, they were technically free. They’d made their way west, where indeed a cabin stood by the riverbend, and they’d mentioned Tsubone’s name to a young lady with long, black hair. She had considered them for a moment before finally revealing that she was Tsubone’s granddaughter, Amane. When Killua asked her if she knew where they could go, Amane had simply nodded. Apparently, her family owned a piece of land deep in the mountains to the north, where they still had an unused cabin. She’d then had to look through a large chest until she had found a key, which she gave to Killua. “Don’t lose it. It’s the only copy,” she’d warned him.

There was not much time to rest after this, considering how close they still were to the Zoldyck estate. Amane had led them to her car, and they had driven down a long stretch of road for most of the day. Alluka had slept a lot, and Killua assumed that was probably a good thing. The less she remembered about this whole ordeal, the better. Amane had eventually left them at a dock, where a ferryman had taken them to another town, and then someone else had led them to a train station and given them two tickets to ride to a town high up into the mountains. From here, someone had picked them up at the station, and honestly, by this point, Killua had trouble keeping track of all the people who had been willing to help them. Each person apparently already knew exactly what to do and where to lead them, and they were all kind to them and willing to give them food and shelter before leading them to their next destination. It had taken them two whole weeks, but at last, Alluka and Killua had ended up hiking into a valley, alone, where they were to look for the old farm that belonged to Tsubone’s family. The relationship was distant enough that the Zoldycks shouldn’t be able to make the connection, at least not right away, and Killua had to admit, the physical distance also brought him a certain form of relief. In this valley, he felt entirely disconnected from Illumi and his father and Hisoka and any other dangers that might have awaited them back at the manor.

Alluka had been delighted to see their new home, especially when she was told they’d be looking after a few goats and planting crops. During their first year at the cabin, someone had visited often to help them learn how to cook for themselves and how to manage a small farm. The work had been hard, but it had also turned out to be surprisingly fun, even rewarding. Killua didn’t have to worry about Alluka’s safety for now, and his sister was more than happy with the daily work and the fresh air.

At night, he would find her sitting in her room, brushing her hair in front of her vanity, singing or laughing, sometimes apparently talking to someone, though he could hear no one else in the room with her. It had taken Killua a whole year to muster up the courage to finally ask Alluka who she was talking to. Alluka had cocked her head and simply pointed to the crystal, as if that explained everything.

“You talk to it?” he asked quizzically, more curious than concerned. By this point, it was just the two of them in the cabin, which helped him feel like they could finally talk freely.

“Of course. She’s my friend, remember?”

Killua suddenly recalled that day by the pond, many years back, when Alluka had told him that she’d made a new friend. He just never expected her to mean it so… literally.

“Her name is Nanika. She told me so herself.” Alluka closed her eyes as she held the crystal, which was once again glowing softly in her hand. “She had been sleeping for a long, long time before she met me, but she remembers that’s the name they gave her. She told me not to tell anyone else about her, but she says you’re ok because I told her you’re nice.”

Killua had laughed, flustered by the fact that his beloved little sister would refer to him as ‘nice’ to her friend, even if her friend was apparently a rock. Still, he wouldn’t dismiss this as Alluka being ‘weak-willed’ or whatever else Illumi had said back in that library. Plus, there was that moment in Alluka’s room where they’d both somehow _floated_ up towards the air duct.

“Is Nanika the one who helped us get out of your room?”

Alluka beamed and nodded enthusiastically. “Uh-huh! There’s lots of things Nanika can do, but she has to be able to see it or touch it first to do something. We’ve been practicing different things, but even she doesn’t remember everything she used to be able to do.”

Killua regarded the glowing crystal, which seemed to shine brighter out here. Did it like the fresh mountain air as much as Alluka did? Or was it something else? He had no idea what to make of the strange stone, but if Alluka said it was okay, then… “Okay, you two should keep practicing. Just make sure you and Nanika don’t do anything to hurt people, okay? That would be bad.”

Alluka had promised, cross her heart and hope to die, and somehow, Killua had felt at ease about the whole crystal business after that. If Alluka promised to be good, then he had a feeling that whatever power resided in that crystal would have to adhere to those rules as well. While Alluka never actually showed Killua what she and Nanika were working on, his sister really did seem to be thriving here, in a place where no one could keep her locked up. The years had gone by at a steady crawl, and things seemed almost unwilling to change. And yet. Killua knew he would never shake the feeling off, that one day it would all come crashing down on them. It had been too easy, too simple, and his family was too stubborn to just give this up. He should know, as he was just as willful as the rest of them. Just as he’d never give up on Alluka, he knew they would never let them go, not as long as they had something of value the family could squeeze out of them.

[*] [*] [*]

Killua is still lost in thought, staring off into the distance as he leans against the railing, and Alluka can recognize a familiar shadow crossing her brother’s face. Before his anxious thoughts bring him down, she decides to distract him and hopefully, cheer him up. “Ki-llu-a!” she calls out, marking each syllable of his name to make sure she gets his attention. Her brother snaps out of it almost immediately, and he stumbles before he rights himself up again and looks at her.

“What is it, sis? Are you ok?” he rushes over to where she’s sat down on the grass. Alluka just points to the kit snuggled up in her lap, who’s munching on her skirt now.

“’course I’m ok, I’m spending quality time with Ember. I’d be even _more_ okay if my big bro were here spending quality time with us too, though.”

Killua looks at all the goats surrounding them and just laughs, plopping down beside her and letting the animals sniff at his clothes. “You’re right, sorry. I was just… remembering something.”

“Something nice?” Alluka asks, though she knows otherwise. Killua manages to offer her a bittersweet smile, but he doesn’t say anything, which just confirms her suspicion. Alluka claps her hands and leans in close to her brother. “Hey, how about this? I’ll make those waffles we wanted to eat last week, and you can use up the last of the whipped cream and the chocolate syrup on yours.”

Killua stares at her, eyes wide, and Alluka is certain she can see her brother’s eyes shimmering slightly. Eventually, he looks away, trying to hide the fact that he’s wiping at his nose, and he nods. “Yeah! Yeah, that sounds like a plan.”

“Okay! But you have to brush Mike today while I make breakfast.” Alluka sticks her tongue out at her brother as she sets the kit down, and then she’s off at a run inside the house before Killua can so much as protest. He spares one last look at all the goats before he stands up and scrambles after her, calling her name and laughing.

As promised, Alluka whips up a delicious breakfast, knowing exactly what her sweet-toothed brother likes best, and he in turn brushes their grumpy sheepdog until his coat glistens and Killua’s sweater and pants are both absolutely covered in dog hair. It’s a fair exchange, especially since Alluka did say he could have the last of their whipped cream (the fact that Killua instead gives it to her is entirely beside the point). The day is otherwise spent much as all the days that have preceded it, with both siblings tending to their little farm and cleaning the house, tasks they’ve become intimately familiar with over the years. Killua takes this as the true celebration of their fifth anniversary here, for isn’t this all he sought out to do when he snuck Alluka out of the house? To get her somewhere where she could be happy again? He doesn’t need a cake and candles to celebrate this milestone, just as he’s never really seen the need to celebrate their birthdays. He knows Alluka is 16 already, while he himself is a few months shy of 18, and no amount of cake and singing is going to change that fact or make time move any faster or slower. Things just… are what they are, and he can’t just change them on a whim.

They’ve settled down on the old couch on the verandah to watch the sun set over the mountains. Alluka claims this is Nanika’s favorite time of day because the clouds turn as pink as her skirt. Killua still isn’t certain how a crystal can see his sister’s clothes, or anything at all, really, but Alluka has never really been able to explain this to him. “She can just see what I see,” is all she tells him. Just as Killua is secretive about that night five years ago, Alluka can be just as secretive when it comes to Nanika and the crystal’s power. And yet, where there should be tension between the siblings, there is instead a mutual sense of understanding, of knowing they have to respect one another’s privacy. They both know there are things they aren’t meant to share, things they’d rather keep to themselves, and neither of them pry where they shouldn’t. Killua can earnestly say he’s never felt more comfortable around anyone else in his life. They get one another, and they help each other out without having to stop and ask for pesky details.

They stay out until the stars start coming out. The moon is barely a sliver in the sky tonight, so the meadow is pitch black. Killua feels as though they’re on an island, surrounded by deep waters. A literal beacon in the dark. Overhead, a shooting star winks past them, and Alluka giggles for some reason. Killua glances at his sister and smiles, wondering what might be so funny. However, they both wordlessly turn their eyes skyward again and listen to the crickets in silence for a moment longer.

“It’s getting cold already,” she suddenly groans with a pout, huddling up under her woolen blanket and cradling a warm mug of tea closer to herself. Killua’s own mug lies forgotten on a table behind them, the contents already growing cold.

“You should head inside, sis. Don’t want you to catch a cold again.” Killua stands up, but Alluka is stubbornly refusing to move from her spot. Killua looks down at her with furrowed brows, but before he can urge her to stand up, Alluka suddenly raises her hand in warning, looking off into the distance.

Killua turns to face the same direction, straining eyes and ears to try and make something out in the darkness. Before he can hear anything, Mike starts to howl, a long, mournful sound. Alluka stands up, her complaints about the cold entirely forgotten. As the dog’s howl echoes through the mountains, another sound joins in. At first faint, but definitely there, a mechanical buzzing that steadily grows louder. Realization sinks into Killua, and he suddenly feels cold. “Alluka, get the lights,” he whispers. “Quickly.”

They both rush into the house, scrambling in a panic towards different rooms to turn off all the lights. Soon enough, they’re plunged in absolute darkness, with only the distant mechanical hum and the sound of their own labored breaths to keep them company.

“Alluka?” Killua calls out to the darkness, trying to find his bearings. The buzzing is near deafening now, made all the more evident by the lack of any other noise in the valley.

“Here!” His sister’s voice is coming from the room next to this one, and Killua carefully makes his way over to her. The faint glow of her crystal leads him to her side, and Alluka clutches one of Killua’s hands tightly in both of her own. He can feel her shaking slightly. “Killua, what’s going on?” she asks, trying to keep her voice down, though Killua can hear the edge of panic in it.

“I don’t know, but I’ve never seen an airship using this route before. It… It might be nothing.”

By now, they can feel the airship’s engines overhead, making the very foundation of the house rumble along with it, and for one blessed moment, Killua thinks it might just pass them by without incident. His hope is short-lived as a spotlight suddenly shines on the house, revealing everything inside in a ghostly white light. Alluka turns to look at him, and their eyes meet for a moment, mirrored panic reflecting off each other’s gaze. Killua is wondering whether to run or hide when the front door slams open and a group of five men rush inside, heading straight for the siblings. Two of them easily tackle Killua to the ground, pinning him to the carpet, while the other three go for Alluka and restrain her. Killua lets out a feral scream, trying to wrestle away from them, but whoever they are, they’re stronger than him and seem to know what they’re doing. All he can do, once again, is just watch as Alluka is knocked unconscious and hauled over to the entrance, where a canvas bag is placed over her head.

“ALLUKA!” he screams, his voice raw and desperate. His sister, however, is unresponsive. Killua struggles in vain, still screaming until his throat burns. It takes him a moment to register his arms have now been tied behind his back, the rope digging into his skin. It doesn’t matter. Whatever happens to him is inconsequential, but Alluka… He has to do something for Alluka before they take her away.

Killua is forced to kneel, and the men hold him tight as a sixth figure walks into the cabin, looking around the room with barely concealed contempt. As the newcomer locks eyes with Killua, he immediately recognizes his brother, Illumi. His heart sinks down to the pit of his stomach.

“So _this_ is where you’ve been holed up these past five years.” It’s a statement, not a question. Illumi’s voice is as deadpan as ever, but Killua can tell his brother is annoyed. And then Illumi _laughs_ , which is somehow even more disconcerting than his usual calm demeanor. “How long did you think you could play this game, Kil? You must’ve known what you were getting into when you sauntered off into the mountains like you did.”

Illumi then turns to look at Alluka, who’s slumped over on the floor right by the spot where they usually left their rainboots on muddy days. He kneels down in one fluid motion and carefully reaches for the crystal at her neck.

“Don’t you touch her,” Killua snarls, his voice hoarse and barely even there. Illumi pulls his hand back, but not because of his brother’s empty threat. He regards Alluka curiously, or rather, he regards the _crystal_ , and then he stands up and dusts his knees off.

“Hm, just as I thought, it’s bonded to her,” he informs the men. “We’ll have to take her too. Bring her onboard. And don’t touch it if you value your hands.” The men grunt in agreement, and between two of them, they haul Alluka up and lead her outside, where Killua gets a glimpse of a mid-sized airship hovering over the meadow, making the grass ripple like ocean waves in a storm. The spotlight, which is attached to the top of the ship, is pointing straight at the house, like an accusing finger. Killua feels dizzy all of a sudden, and he knows he wouldn’t be able to stand even if he wanted to.

“Alluka…” Killua whispers, watching helplessly as they haul his sister away. “Wait, don’t…”

“Now, now, Kil.” Illumi makes his way over to him, towering over him as he pulls Killua by the hair to make him look at up him. “You don’t think I’d just _abandon you_ in the middle of nowhere like this, do you? It’s my job to look after the whole Zoldyck family, even the black sheep who’ve strayed too far. Enough games. You’re coming back home with me too, little brother.”

“We’re _never_ going back there,” Killua hisses, baring his teeth at Illumi. His brother, however, just looks slightly disappointed about the outcome. He lets go of Killua’s hair and turns around without so much as a backward glance.

“Too bad. I thought you’d come willingly. Bring him onboard too. Quickly. This whole place smells like a stable.” Illumi raises a hand to give an order, and Killua grunts as he feels a sharp blow to the back of his head. His vision starts blurring around the edges, and the last thing he sees is his brother wading through the field toward the airship, hair billowing out behind him like a pair of dark wings, before everything goes black.

**Notes for the Chapter:**

> The chapter ended up being longer than expected because it was so exposition-heavy. I hope you're into flashbacks because boy oh boy, was that one big Flashback. Thankfully, next chapter we'll be moving along with the story, and we should be picking up in the airship. I hope you're ready for some more Zoldyck family drama. Sadly, no Gon until chapter 3, but I'm always happy to write more Killua + Alluka.
> 
> Thank you for reading! I really appreciate each and every one of my readers. See you next chapter!


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